Alarm goes off when key turns: Low Drive Lube Monitor

DJnovice

Recruit
Joined
Oct 11, 2024
Messages
5
We just got a 2000, 20' Astro deck boat with a 4.3 MerCruiser, Thunderbolt Ignition.
It ran beautifully for three weeks. Then an alarm went off. When I turn the key, the alarm goes off. The engine will start, but the alarm stays on.
I am new to boat engines.
When I raised the engine cover, the Drive Lube Monitor container showed low levels.
Two novice questions:
1) What is the best product to add?
2) Where/how is the product added?

Boat Motor MerCruiser 4.3 Thunderbolt.jpegBoat Drive Lube Monitor photo-LOW.jpegBoat Drive Lube Monitor LOW side view.jpeg
 

Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,291
What drive? standard A1 use 80-85-90 Wt gear oil or the Hi-Perf green oil
For a Bravo, the green Hi-Perf oil made for the cone clutch
If after you refill it and the alarm silences it means the gear oil leaked out and you need to service the drive and repair the leak
 

DJnovice

Recruit
Joined
Oct 11, 2024
Messages
5
What drive? standard A1 use 80-85-90 Wt gear oil or the Hi-Perf green oil
For a Bravo, the green Hi-Perf oil made for the cone clutch
If after you refill it and the alarm silences it means the gear oil leaked out and you need to service the drive and repair the leak
Thanks so much. I'm not sure what drive this is. Where could I look to find that information?
 

Fun Times

Moderator
Staff member
Joined
May 16, 2009
Messages
9,046
Usually Walmart will have some Quicksilver/Mercruiser High Performance gear lube in the small marine section for a bit lower cost vs a local marine shop/dealer has to sell it for… but the following link is what one design will look like or the Mercruiser bottle version will be black while this one is silver colored all in which is the correct oil type you’ll need to use here.


In your case, just dump some in until you fill it to the max line on the reservoir bottle.

If you were going to change the entire sterndrive gear lube from the stern drive to the bottle, then you’d drain it from the lower unit housing kind of by the propeller then pump new oil back up from the bottom to the reservoir.
 

Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,291
simply refilling the bottle DOES NOT mean your outdrive is full.
You need to find out where the oil went to ,if the drive is already dry, just filing the bottle will NOT prevent drive destruction
 

Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,291
And get rid of those Batwing manifolds before they start ;eaking
 

DJnovice

Recruit
Joined
Oct 11, 2024
Messages
5
Usually Walmart will have some Quicksilver/Mercruiser High Performance gear lube in the small marine section for a bit lower cost vs a local marine shop/dealer has to sell it for… but the following link is what one design will look like or the Mercruiser bottle version will be black while this one is silver colored all in which is the correct oil type you’ll need to use here.


In your case, just dump some in until you fill it to the max line on the reservoir bottle.

If you were going to change the entire sterndrive gear lube from the stern drive to the bottle, then you’d drain it from the lower unit housing kind of by the propeller then pump new oil back up from the bottom to the reservoir.
Worked perfectly. I went to the boat shop that the previous owner used. Bought the gear lube, and filled it to the max line. The alarm stopped. I checked. The level is stable. Thank you!
 

DJnovice

Recruit
Joined
Oct 11, 2024
Messages
5
simply refilling the bottle DOES NOT mean your outdrive is full.
You need to find out where the oil went to ,if the drive is already dry, just filing the bottle will NOT prevent drive destruction
Yes. We'll pull the boat later this week to track down the leak.
 

JonBoat55

Seaman
Joined
Aug 26, 2019
Messages
55
Definently take the time to find that leak proper. Its tempting to forget about it after it seems to be holding oil and running well. It will run great until it doesnt and then its too late.
 

Scott06

Admiral
Joined
Apr 20, 2014
Messages
6,424
Definently take the time to find that leak proper. Its tempting to forget about it after it seems to be holding oil and running well. It will run great until it doesnt and then its too late.
Exactly, last winter I got fishing line around prop seal, when I pressure tested shift shaft seal was also leaking … so I reassessed the whole drive. Most seals were in perfect shape, figured at this point I’ll be good for another 18 years
 
Top